The present invention pertains to crop mark setting devices in printing presses, in which a web conveyed endlessly is, or preferably a plurality of such webs are, printed on. Furthermore, the present invention pertains to a process for setting the crop mark of printed web strands, which were obtained from one or more webs by lengthwise cutting. The printing press is preferably a web-fed printing press, in which the web or the plurality of webs are unwound continuously from a roll each. The present invention is used especially preferably in the web-fed rotary printing of large numbers of newspaper copies.
At least two prints arranged next to each other are printed continuously on the web or usually on a plurality of webs in the running print production. When viewed in the direction of delivery, the same print or a periodic sequence of two or, in principle, even more different prints may be printed on the web one after another. The web is, or the plurality of webs are, cut lengthwise into web strands between the prints arranged next to each other. A plurality of web strands are converged into a bundle corresponding to the running print production and cut together at right angles to the direction of delivery of the particular bundle in order to obtain the individual printed products, e.g., newspapers or magazines. In general, a plurality of bundles are converged and cross-cut together in newspaper printing to obtain the printed product. The web strands that form a bundle each are converged such that the prints of the web strands of one bundle are centered as accurately as possible between two cuts following each other in the direction of delivery. To obtain their so-called crop mark, i.e., for centering between the cuts, the web strands of one bundle are influenced by means of suitable operations. With respect to the individual web strand, these operations are changes in the path length that the web strand travels between the site of printing and the site of cross cutting, these changes being performed specifically with respect to the crop mark of the web strand in question. The crop mark position of the strand in question or, briefly, the crop mark of the strand is set by specifically changing the path length.
Compensator rollers have proved successful for setting the crop mark. The compensator rollers are wrapped around by a web strand each, usually by 180xc2x0. The path of the web strand wrapping around the compensator roller is lengthened or shortened by an adjusting movement of a compensator roller at right angles to its longitudinal axis, and the crop mark of the web strand in question is thus set.
In prior-art printing presses, a printed web strand is guided over an array of turning bars and is turned and/or reversed there. After the turning and/or reversing, the operations suitable for setting the crop mark are performed with the web strand, and the web strand is finally converged with one or more other web strands and cross-cut.
The pulling in of a new web strand is complicated in the prior-art crop mark setting devices. The problem is made more acute by the generally crowded space conditions in the environment of compensator rollers. The compensator rollers must, furthermore, have twice the width of the web strand to be treated, because the web strand may be turned in one print production and reversed in the others.
The object of the present invention is to design a crop mark setting device and a process for setting the crop mark such that a new web strand can be pulled in mechanically via a compensator roller or another, likewise suitable reversing means of the crop mark setting device.
The present invention pertains to a printing press with at least one printing couple for printing on a web, a lengthwise cutting means, a means for converging web strands, a crosscutting means and a crop mark setting device. At least two prints arranged next to each other are printed continuously on the web in the printing couple. The printed web is cut lengthwise between the prints into a first web strand and at least one other, second web strand by a lengthwise cutting means. The lengthwise cutting means may also be arranged in front of the printing couple and cut the yet unprinted web strand into at least two web strands, which are printed on strand by strand only thereafter. The means for converging web strands comprises a turning bar means for turning and/or reversing the second web strand. The second web strand is preferably converged with the first web strand. In principle, the first web strand and the second web strand may, however, also be converged with one or more other web strands each to form another web strand bundle each. The cross-cutting means is used to cross-cut a web strand bundle comprising at least the second web strand, and preferably also the first web strand. The crop mark setting device comprises a frame, a first deflecting means for deflecting the first web strand around a first deflection axis and an additional, second deflecting means for deflecting the second web strand around a second deflection axis. The second deflecting means is mounted movably in the frame in relation to the first deflecting means such that the length of the path that is traveled by the second web strand is changed relative to the length of the path of the first web strand by a movement of the second deflecting means in relation to the first deflecting means. Even though the deflecting means may, in principle, be formed by rollers or other deflecting bodies, especially rotatably mounted rotary bodies, which are arranged next to each other along the particular deflection axis, each of the deflecting means is, however, formed as a roller in the manner of the prior-art compensator rollers, especially preferably as a regular cylindrical roller.
At least the second deflecting means, i.e., the deflecting means for the second web strand to be led through the turning bar means, is arranged according to the present invention in front of the turning bar means. The second web strand can be pulled in due to this measure mechanically in a simple manner up to the turning bar means.
The arrangement of the first deflecting means in front of the turning bar area is also advantageous, e.g., if the first web strand is to be turned and/or reversed in the turning bar means. However, arranging the two deflecting means at right angles to the web strands next to each other, in which case the deflection axes formed by them preferably extend in the same plane, is always advantageous, even when the first web strand is conveyed farther directly, i.e., without turning and/or reversing, bypassing the turning bar means, and is converged with the second web strand or one or more other web strands printed on in the printing press to form a web strand bundle. The deflecting means for the web strands of the web are arranged in a preferred embodiment of the present invention such that a web that has not yet been cut lengthwise can be pulled at the same time around the deflecting means, as a result of which the mechanical pulling in of the web is considerably facilitated. No other deflecting means, which would be wrapped around by only a single one of the web strands of the web, are arranged between the deflecting means to achieve this. They are preferably even arranged next to one another in the sense that no other deflecting means for the web are arranged between them in the path of the web. Lengthwise cutting is preferably performed during the pulling in of the web only when the web has been pulled in by the crop mark setting device thus formed.
The arrangement of the deflecting means for the single web strand or for the plurality of web strands of the web in front of the turning bar means has the additional advantage, besides the simplification of the mechanical pulling in of the web, that the associated deflecting means may have the width of a single web and it no longer needs to have the double width of the web as before.
In the embodiment in which the deflecting means are arranged next to each other at right angles to the web strands in close proximity in space, they are preferably supported on one side each of the frame only, while they project with a free end each in the direction of the respective other side of the frame. Due to an adjusting movement taking place between the two deflecting means, the two deflecting means can be preferably brought into a position in which they are flush with one another and form a preferably cylindrical, smooth, uniform surface for the web to be pulled in.
It is sufficient in simple embodiments to mount only the second deflecting means movably in the frame to perform adjusting movements. However, the first deflecting means is preferably also mounted movably in the frame. The movable mounting of the first deflecting means as well is advantageous, e.g., when the first web strand is to be turned and/or reversed in one print position or another. However, the movable mounting of the second deflecting means is also advantageous if the first web strand is neither turned nor reversed before the bundle formation, but is converged as a direct strand with the second web strand and/or with one or more other web strands. New possibilities of crop mark setting are opened up precisely for this case, when the extent of the mobility is only great enough. A maximum length of the adjustment path of the first deflecting means should be at least half the maximum length of an adjustment path of the second deflecting means. It is even more preferred if it is at least essentially or exactly as great as the maximum length of the adjustment path of the second deflecting means.
In a preferred process for setting the crop mark, in which the first web strand forms a direct strand of a web strand bundle, the path length of the first web strand is changed as well, namely, in agreement with the additional web strand of the bundle or the plurality of additional web strands of the bundle. If, e.g., only the first web strand and the second web strand form a web strand bundle, the crop mark positions of the two web strands can be set by essentially equal, preferably exactly equal adjustment paths of the first deflecting means and the second deflecting means. It is no longer necessary now to compensate the entire position difference or at least the substantially greater part of the position difference in the second web strand, but only approximately or exactly half the position difference, while the remaining rest is compensated in the direct strand. This also applies in the same manner to the case in which the first web strand and the second web strand are also converged with additional web strands or the first web strand is not converged with the second web strand but only with another web strand or other web strands to form a web strand bundle. The crop marks of the web strands per bundle are set in such a way that the setting time needed for setting all crop marks of these web strands is reduced or preferably even minimal compared with the prior-art setting process. The greatest adjustment path that an individual deflecting means of these deflecting means must perform can be reduced and preferably minimized by coordinated adjusting movements of the deflecting means, which act on the web strands of the bundle and are used to set the crop mark. Since the time needed for setting the crop marks of all web strands of a bundle is proportional to the greatest of the adjustment paths that one or more of the deflecting means must travel or is at least determined by the greatest of the adjustment paths at equal speed of adjustment of the deflecting means, the setting time and, as a result, spoilage are reduced.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.